U.S. patent number 6,476,387 [Application Number 09/311,268] was granted by the patent office on 2002-11-05 for method and apparatus for observing or processing and analyzing using a charged beam.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Junzou Azuma, Yuichi Hamamura, Hidemi Koike, Yasuhiro Koizumi, Michinobu Mizumura, Norimasa Nishimura, Akira Shimase.
United States Patent |
6,476,387 |
Nishimura , et al. |
November 5, 2002 |
Method and apparatus for observing or processing and analyzing
using a charged beam
Abstract
In a method for observing or processing and analyzing the
surface of a sample by irradiating a charged beam on the sample
covered at least partially by an insulator film, an ultraviolet
light is irradiated possibly as pulse on the sample (substrate),
thereby transforming the insulator into a conductive material due
to the photoconductivity effect, thereby transforming the surface
of the sample (substrate) into a conductive material, so that
charged particles are grounded from a grounded portion in order to
prevent the charged beam from being repulsed due to charged
particles of the irradiated charged beam accumulated in the
insulator formed on the surface of the sample (substrate).
Inventors: |
Nishimura; Norimasa (Yokohama,
JP), Shimase; Akira (Yokosuka, JP), Azuma;
Junzou (Ebina, JP), Hamamura; Yuichi (Yokohama,
JP), Mizumura; Michinobu (Yokohama, JP),
Koizumi; Yasuhiro (Sayama, JP), Koike; Hidemi
(Hitachinaka, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
15093199 |
Appl.
No.: |
09/311,268 |
Filed: |
May 14, 1999 |
Foreign Application Priority Data
|
|
|
|
|
May 15, 1998 [JP] |
|
|
10-132946 |
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Current U.S.
Class: |
850/9; 250/307;
250/310; 250/398; 250/492.2; 250/492.3; 250/504R; 430/273.1;
430/296; 850/16 |
Current CPC
Class: |
H01J
37/28 (20130101); H01J 2237/0047 (20130101); H01J
2237/2482 (20130101) |
Current International
Class: |
H01J
37/28 (20060101); H01J 037/30 () |
Field of
Search: |
;250/306,307,310,398,54R,492.2,492.3 ;430/296,273.1 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
5441849 |
August 1995 |
Shiraishi et al. |
5591970 |
January 1997 |
Komano et al. |
|
Foreign Patent Documents
Other References
Japanese Patent Abstract No. 1-243449 published Sep. 28, 1989.
.
Japanese Patent Abstract No. 57-170526 published Oct. 20, 1982.
.
Japanese Patent Abstract No. 1-119668 published May 11,
1989..
|
Primary Examiner: Lee; John R.
Assistant Examiner: Wells; Nikita
Attorney, Agent or Firm: Antonelli, Terry, Stout &
Kraus, LLP
Claims
What is claimed is:
1. A method of observing or processing and analyzing the surface of
a sample using a charged beam, comprising the steps of: irradiating
said charged beam on the surface of a sample covered at least
partially by an insulator film; irradiating light only to a portion
of the surface of the sample exciting the electrons in a material
composing said insulator film in an area including a charged beam
irradiation portion on the surface of said sample; detecting
secondary particles generated from the surface of said sample by
irradiating said charged beam on the surface of said sample; and
observing, processing, or analyzing the surface of said sample
according to the information of said detected secondary
particles.
2. A method of observing or processing and analyzing the surface of
a sample in accordance with claim 1, wherein the timing of said
step for irradiating said charged beam on the surface of a sample
is set differently from the timing of said step for exciting the
electrons in said insulator by irradiating said light.
3. A method of observing or processing and analyzing the surface of
a sample in accordance with claim 1, wherein said light is an
ultraviolet light.
4. A method of observing or processing and analyzing the surface of
a sample in accordance with claim 1, wherein said ultraviolet light
is irradiated from a plurality of directions.
5. A method of observing or processing and analyzing the surface of
a sample in accordance with claim 1, wherein said ultraviolet light
is irradiated in an area including a grounded conductor.
6. A method of observing or processing and analyzing the surface of
a sample in accordance with claim 1, wherein the wavelength of said
ultraviolet light is 150 nm or under.
7. A method of observing or processing and analyzing the surface of
a sample using a charged beam, comprising the steps of: placing a
sample on a sample stage provided in a sample chamber, said sample
being covered at least partially by an insulator film; irradiating
said charged beam on the surface of said sample while said sample
is placed on said sample stage and said sample chamber is
evacuated; irradiating light only to a portion of the surface of
said sample in an area ranged from a charged beam irradiation
portion on the surface of said sample to the surface of a member
grounded in said sample chamber, said light operating to excite the
electrons in a material composing said insulator film; detecting
secondary particles generated from the surface of said sample by
irradiating said charged beam on the surface of said sample; and
observing, processing, or analyzing the surface of said sample
according to the information of said detected secondary
particles.
8. A method of observing or processing and analyzing the surface of
a sample in accordance with claim 7, wherein said light is an
ultraviolet light.
9. A method of observing or processing and analyzing the surface of
a sample in accordance with claim 7, wherein said ultraviolet light
is irradiated from a plurality of directions.
10. A method for observing or processing and analyzing the surface
of a sample in accordance with claim 7, wherein the wavelength of
said ultraviolet light is 150 nm or under.
11. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam, comprising: a charged
beam source for emitting a charged beam; a focusing optical system
for focusing a charged beam emitted from said charged beam source,
thereby irradiating a focused beam on said sample; a stage for
holding said sample thereon; secondary particle detecting means for
detecting secondary particles generated from said sample by
irradiating said charged beam focused by said focusing optical
system on said sample; and irradiating means for irradiating an
ultraviolet light only to a portion of on the surface of said
sample.
12. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
11, wherein said irradiating means irradiates an ultraviolet light
on the surface of said sample from the same axial direction as that
of said focusing optical system means.
13. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
11, wherein said irradiating means irradiates said ultraviolet
light on the surface of said sample from a plurality of
directions.
14. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
11, wherein said charged beam source emits an electron beam or an
ion beam.
15. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
11, wherein said apparatus observes, processes, or analyzes the
surface of said sample by irradiating said focused charged beam on
the surface of said sample.
16. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam, comprising: a sample
chamber provided with a sample stage for holding a sample therein;
evacuating means for evacuating said sample chamber; a charged beam
source for emitting a charged beam; a focusing optical system for
focusing said charged beam emitted from said charged beam source
and irradiating a focused charged beam on the surface of said
sample placed on said sample stage; secondary particle detecting
means for detecting secondary particles generated from said sample
by irradiating said charged beam focused by said focusing optical
system on said sample; and ultraviolet light irradiating means for
irradiating an ultraviolet light only to a portion of the surface
of said sample in a charged beam irradiation area ranged from a
charged beam irradiation portion on the surface of said sample to
the surface of a member grounded in said sample chamber.
17. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
16, wherein said irradiating means irradiates said ultraviolet
light on the surface of said sample from the same axial direction
as that of said focusing optical system means.
18. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
16, wherein said irradiating means irradiates said ultraviolet
light on the surface of said sample from a plurality of
directions.
19. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
16, wherein said charged beam source emits an electron beam or an
ion beam.
20. An apparatus for observing or processing and analyzing the
surface of a sample using a charged beam in accordance with claim
16, wherein said apparatus observes, processes, or analyzes the
surface of said sample by irradiating said focused charged beam on
the surface of said sample.
21. A method of observing or processing and analyzing the surface
of a sample in accordance with one of claims 1 to 10, wherein said
light is irradiated in the form of pulses.
22. An apparatus for observing or processing and analyzing the
surface of a sample in accordance with one of claims 11 to 20,
wherein said irradiating means produces light in the form of
pulses.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for
observing or processing and analyzing substrates with an insulator
formed thereon using a charged beam; and; more particularly, the
invention relates to a method and an apparatus of the type
described, which can prevent charged particles from accumulating in
an insulator irradiated by the charged beam, as well as to detect
secondary electrons generated from those substrates as secondary
particles.
At present, a charged beam is used for observing or analyzing and
processing minute areas on LSI circuits, masks, etc. However, the
method and apparatus used heretofore for such objects have
experienced a problem in that, when observing or analyzing and
processing substrates with an insulator formed thereon using a
charged beam, the charged particles of the irradiated charged beam
are accumulated (charging up) on the surface of the object
insulator, with a result that the charged beam is repulsed, causing
the irradiation point of the charged beam to be shifted, thereby
disabling the observation or analysis and processing of the
substrate. On the other hand, there is a conventional method that
uses an ion beam to achieve the above-described operations, as
disclosed in the official gazette of Japanese Patent Laid-Open No.
61-248346. According to this method, an electron shower is
irradiated in the ion beam irradiation area, thereby neutralizing
electrons which may have accumulated on the surface of the object
substrate. The surface of the substrate can thus be observed,
analyzed, and processed using a scanning ion microscope image
obtained by detecting secondary ions ejected from the substrate
during ion beam irradiation.
Since the above conventional technique uses an electron shower, it
is impossible to obtain images from secondary electrons detected as
secondary particle images. Consequently, the surface of the object
substrate can be observed only by images obtained from secondary
ions detected as described above. Furthermore, this case also
experiences a problem in that high contrast images cannot be
obtained, since the amount of secondary ions is as low as a few
percent of the primary ions. This is why the positioning accuracy
during irradiation of the charged beam is lowered. On the other
hand, the official gazettes of the Japanese Patent Laid-Open No.
1-119668, No. 57-170526, and No. 1-243449 have disclosed methods of
preventing the above-mentioned problems. According to those
methods, the insulator formed on the object substrate is
transformed into a conductive material by exciting the electrons
therein optically so as to prevent a charging-up from occurring in
the insulator. And accordingly, this method makes it possible to
obtain images with secondary electrons detected as images of
secondary particles.
The official gazette of the Japanese Patent Laid-Open No. 1-119668
has also disclosed a method of irradiating the substrate with an
ultraviolet beam having a difference of energy between the
conductor bands of Si and SiO2 or a difference of energy between
valence bands. According to this method, an energy must be injected
in the interface between Si and SiO2 It is thus impossible to use a
short wavelength light that cannot pass through SiO2. In addition,
it is also difficult to apply the method to substrates, which tend
to block the light applied to the interface due to having a
light-proof film, such as a mask, etc., as well as substrates which
are not made of a conductive material.
Another method of preventing the surface of a light-exposed
substrate from charging-up is disclosed in the official gazette of
Japanese Patent Laid-Open No. 57-170526. According to this method,
an organic semiconductor provided with optical conductivity is used
or a semiconductor provided with optical conductivity is coated on
the object resist. This method also includes problems in that a
coating process is needed, as well as the fact that the kinds of
samples which are capable of use are limited; and so, the method
cannot be used for masks, and the like.
The official gazette of Japanese Patent Laid-Open No. 1-243449 has
disclosed another method of preventing such charging-up. According
to this method, light for exciting the object insulator is applied
obliquely, so charging-up is apt to occur at portions on the
substrate which are not irradiated by the light due to the
projections and depressions formed thereon. In addition, it is also
difficult for this method to prevent charging-up at samples covered
completely by an insulator and isolated mask patterns even when the
electrons in the insulator are excited, since there is no concrete
method for grounding the charged electrons.
SUMMARY OF THE INVENTION
Under such circumstances, it is an object of the present invention
to provide a method and an apparatus with which it is possible to
observe or analyze and process respective substrates with an
insulator formed thereon accurately and easily by solving the
above-described conventional problems.
What makes it difficult to observe images of secondary particles on
a substrate with an insulator formed thereon is charged particles
that are not grounded, but are accumulated (charging-up) in the
insulator. And, those accumulated charged particles cause the
irradiated charged beam to be repulsed.
This is why it is considered to be possible to prevent such the
charging-up if the surface of the substrate is transformed into a
conductive material and grounded. And, the present invention has
achieved this object by irradiating a light having a wavelength for
exciting the electrons in the insulator on the object substrate,
thereby transforming the insulator into a conductive material due
to the photoconductivity effect, and then grounding the charged
particles from the grounded surface.
The present invention has also achieved the above objects by
employing a method that uses a charged beam and includes the
following steps. Concretely, the method includes a step of placing
a sample covered at least partially by an insulator film on a
sample stage provided in a sample chamber, a step of irradiating
light, possibly as pulses on the surface of the sample while the
sample is placed on the sample stage and the sample chamber is
evacuated, a step for irradiating the charged beam on the surface
of the sample, a step of irradiating a light like pulses in an area
ranged from a charged beam irradiation portion to the surface of a
member grounded in the sample chamber so as to excite the electrons
in the material composing the insulator film, a step of detecting
secondary particles generated from the surface of the sample
irradiated by the charged beam, and a step of observing,
processing, or analyzing the surface of the sample according to
information provided by the secondary particles detected in the
preceding step.
The present invention has also achieved the above objects by
employing a method that uses a charged beam and includes the
following steps. Concretely, the method includes a step of placing
a sample covered at least partially by an insulator film on a
sample stage provided in a sample chamber, a step of irradiating
light, possibly as pulses on the surface of the sample while the
sample is placed on the sample stage and the sample chamber is
evacuated, a step for irradiating the charged beam on the surface
of the sample, a step of irradiating a light like pulses in an area
ranged from a charged beam irradiation portion to the surface of a
member grounded in the sample chamber so as to excite the electrons
in the material composing the insulator film, a step of detecting
secondary particles generated from the surface of the sample
irradiated by the charged beam, and a step of observing,
processing, or analyzing the surface of the sample according to
information provided by the secondary particles detected in the
preceding step.
Furthermore, the present invention has also achieved the above
objects with an apparatus that uses a charged beam and includes the
following components. Concretely, the apparatus of the present
invention comprises a charged beam source for emitting a charged
beam, a focusing optical system for irradiating the charged beam on
the sample by focusing a charged beam emitted from the charged beam
source, a stage for holding the sample thereon, secondary particle
detecting means for detecting secondary particles generated from
the sample irradiated by the charged beam focused by the optical
focusing means, and irradiating means for irradiating ultraviolet
light, possibly as pulses, on the surface of the sample.
Furthermore, the present invention has achieved the above objects
with an apparatus that uses a charged beam and includes the
following components. Concretely, the apparatus of the present
invention comprises a sample chamber provided with a sample stage
on which a sample is placed, evacuating means for evacuating the
sample chamber, a charged beam source for emitting a charged beam,
a focusing optical system for focusing the charged beam emitted
from the charged beam source, thereby irradiating a focused charged
beam on the sample placed on the sample stage, secondary particle
detecting means for detecting secondary particles generated from a
sample irradiated by the charged beam focused by the optical
focusing system, and ultraviolet light irradiating means for
irradiating ultraviolet light, possibly as pulses, in an area
ranged from a charged beam irradiation portion on the surface of
the sample to the surface of a member grounded in the sample
chamber.
According to the present invention, therefore, it is easy to
observe, process, and analyze substrates with an insulator formed
thereon. Especially, it is possible to detect and correct defects
on phase shifting masks. Furthermore, even for substrates composed
of only an insulator, it is possible to observe, process, and
analyze those substrates if a grounded probe or conductor exists in
the light irradiation area and is in contact with the
substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1(a) and 1(b) are diagrammatic views of the apparatus for
performing the correcting method in accordance with the first
embodiment of the present invention; wherein, FIG. 1(a) is a
schematic front across sectional view of the apparatus of the
present invention, and FIG. 1(b) is an expanded view of a portion
of FIG. 1(a).
FIG. 2 is a schematic front view showing the relationship among a
sample, a beam source, and a photoelectric multiplier in an
apparatus employing the correcting method in accordance with the
second embodiment of the present invention.
FIG. 3 is a schematic front cross sectional view of a sample and
the area around the sample in an apparatus employing the method for
observing, processing, and analyzing in accordance with the third
embodiment of the present invention.
FIG. 4 is a schematic front cross sectional view of a sample and
the area around the sample in an apparatus employing the correcting
method in accordance with the fourth embodiment of the present
invention.
FIG. 5 is a schematic front cross sectional view of a sample and
the area around the sample in an apparatus employing the correcting
method in accordance with the fifth embodiment of the present
invention.
FIG. 6 is a schematic front cross sectional view of a sample and
the area around the sample in an apparatus employing the correcting
method in accordance with the sixth embodiment of the present
invention.
FIG. 7(a) is a schematic front cross sectional view of a sample and
the area around the sample in an apparatus employing the grounding
method in accordance with the seventh embodiment of the present
invention, and FIG. 7(b) is a top view of the sample.
FIG. 8 is a schematic front cross sectional view of a sample and
the area around the sample in an apparatus employing the grounding
method in accordance with the eighth embodiment of the present
invention.
FIG. 9 is a schematic front cross sectional view of a sample and
the area around the sample in an apparatus employing the
irradiating method in accordance with the ninth embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereunder, the preferred embodiments of the present invention will
be described with reference to the accompanying drawings, which
embodiments will be described individually for simplifying the
description.
<First Embodiment>
FIG. 1(a) shows the first embodiment of the present invention. In
this embodiment, an ion beam is used as a charged beam and a phase
shifting mask is used as a sample provided with an insulator formed
thereon.
In FIG. 1(a), in an ion beam chamber 16 there is provided an ion
beam optical system comprising an ion source 1, a lens 3 for
focusing an ion beam 2 emitted from, for example, both a Ga and ion
source 1, and a deflecting electrode 4 for deflecting the ion beam
2. Those components of the optical system are powered by a power
supply and controlled by a controller (both not illustrated). The
ion beam chamber 16 is evacuated by an evacuating apparatus through
an evacuation tube 17.
In a process chamber 15 there are provided a holder 12 for holding
a sample 11, a clamp 13 for clamping the sample 11, an XY stage 14
for moving the sample 11 to a given position, a scintillator 5 for
detecting secondary particles ejected from the sample irradiated by
the ion beam 2, a secondary particle detector 6 comprising a
photoelectron multiplier, and a reflecting mirror 9 for irradiating
light 8 for exciting the electrons in an insulator formed on the
sample 11. The light 8 is emitted from the exciting light source 7
attached to the process chamber 15 and is irradiated on the sample
in a uniform manner. The reflecting mirror 9 is provided with a
hole 10 through which the ion beam is passed. The process chamber
15 is evacuated by an evacuating apparatus (not illustrated)
through the evacuation tube 17.
A reserved chamber 19 is connected to the process chamber 15
through a gate valve 18, and the reserved chamber 19 is structured
so as to guide a holder 12 onto the XY stage 14 using a transfer
device (not illustrated).
Hereunder, a method of observing a processing substrates with an
insulator formed thereon using the apparatus in this example will
be described more in detail with reference to FIG. 1(b). FIG. 1(b)
shows a detailed view of an area where the ion beam is irradiated.
In FIG. 1(b), numeral 20 denotes a conductive light-proof film, 21
denotes a phase shifter, 22 denotes a defect, 23 denotes a power
supply for applying a voltage to the scintillator 5, and 24 denotes
a power supply for applying a voltage to the reflecting mirror. For
example, if the defect 22 is detected on the phase shifter 21
provided in the phase shifting mask, the phase amplitude of the
light that passes the defect portion is shifted significantly. When
the ion beam 2 is used to correct this defect, therefore, a defect
22 is detected at first using the defect inspecting device. Then,
the possible defect position is moved to a location just under the
light axis of the ion beam 2 according to the coordinate data which
identifies the defect position. After this, the light 8 for
exciting the electrons in the object insulator is irradiated on the
defect 22 from the light source 7.
The light 8 for exciting the electrons in the insulator is
irradiated in a uniform manner in the ion beam irradiation area in
the same axial direction as that of the ion beam. In addition, the
light 8 can be irradiated up to the conductive light-proof film 20,
which is grounded by a substrate holder, and thereby the electrons
in the insulator region are grounded. The insulator formed on the
transparent substrate 11 provided with insulation properties is
transformed into a conductive material, since the electrons in the
valence band are excited up to a conductor band. Consequently, the
charged particles in the irradiated ion beam 2 are not accumulated
in the insulator; rather, they are ejected up to the grounded
portion. After this, the secondary particles discharged from the
surface of the substrate are detected by the secondary particle
detectors 5 and 6 when the ion beam 2 is scanned on the substrate.
The scanning ion image can thus be observed.
In this case, if a voltage is applied on the reflecting mirror 9
and the surface of the substrate is made of a material having a
large probability for ejecting secondary particles, the secondary
particles can be amplified using the reflecting mirror 9 to which a
voltage is applied.
If the intensity of the light 8 for exciting the electrons in the
insulator is varied with time, secondary particles can be detected
more effectively using the secondary particle detectors 5 and 6 by
adjusting those detectors 5 and 6 to the varying intensity of the
light 8. And, according to the scanning ion image obtained above,
the position of the defect 22 of the phase shifter is detected, the
irradiation area of the ion beam 2 is set, and the ion beam 2 is
irradiated only on the defect portion, thereby removing or
correcting the defect 22. In addition, if the wavelength of the
light 8 for exciting the electrons in the insulator can excite the
transparent substrate 11 provided with insulation properties and
the substrate 11 is made of quartz, an ultraviolet light should
preferably be used at a wavelength of 150 nm or under.
<Second Embodiment>
The second embodiment of the present invention involves a method of
detecting and correcting defects of a phase shifter by irradiating
light for exciting the electrons in the object insulator on each
defect from two directions. Hereunder, the method will be described
with reference to FIG. 2. In FIG. 2, numeral 25 denotes a prism.
Just like the first embodiment, an ion beam 2 is used for
correcting defects. At first, the position of an object defect is
detected using a defect inspecting unit, and according to the
coordinate data which identifies the defect position, the possible
position of the defect 22 is moved to a location just under the
light axis of the ion beam 2. Then, the light 8 for exciting the
electrons in the object insulator is irradiated from the light
source 7. Part of the light 8 enters the prism 25 and the rest of
the light 8 is directed to the scintillator 5. The light 8 which
enters the prism 25 is then deflected so as to be irradiated on the
ion beam irradiation area.
The light irradiated onto the scintillator 5 is reflected by the
reflecting film formed on the surface of the scintillator 5, so
that the light is irradiated in the ion irradiation area from a
direction different from that of the light irradiated from the
prism 25. The light 8 is irradiated up to the conductive
light-proof film 20 grounded by the substrate holder, and thereby
the electrons in the insulator are grounded. The insulator formed
on the transparent substrate 11 provided with insulation properties
is transformed into a conductive material due to the irradiation of
the light 8, as in the first embodiment, so that the charged
particles of the ion beam 2 are not accumulated in the insulator;
rather, they are ejected up to the grounded portion. After this,
the secondary particles ejected from the surface of the substrate
are detected by the secondary particle detectors 5 and 6 when the
ion beam 2 is scanned on the substrate. The scanning ion image can
thus be observed.
The position of the defect 22 of the phase shifter is detected from
this scanning ion image. The ion beam 2 is then irradiated only on
this defect portion, thereby removing or correcting the defect 22.
In addition, if the wavelength of the light 8 for exciting the
electrons in the insulator can excite the transparent substrate 11
provided with insulation properties and the substrate 11 is made of
quartz, an ultraviolet light should preferably be used at a
wavelength of 150 nm or under. The scintillator 5 should not react
with the light 8.
<Third Embodiment>
The third embodiment of the present invention is shown in FIG. 3.
In this embodiment, an ion beam is used as a charged beam and light
generated from a plasma is irradiated on the sample provided with
insulation properties from many directions, thereby observing,
processing, and analyzing the sample. In FIG. 3, numeral 26 denotes
a sample provided with insulation properties, 27 denotes a light
transmission material that transmits light for exciting an object
insulator, 28 denotes an electrode for generating a plasma, 29
denotes a plasma chamber, 30 denotes a plasma having a wavelength
for exciting the electrons in the object insulator, and 31 denotes
a high frequency power supply. Because secondary particle images
are also shifted by charging-up even on the surface of the object
insulator, other than a phase shifting mask, an ion beam 2 is used
for observing, processing, and analyzing the sample in this
embodiment, just like in the above embodiments.
At first, the object portion for observing, processing, and
analyzing is moved to a location just under the light axis of the
ion beam 2, and then the plasma 30 is ignited in the plasma chamber
29 just under the sample 26 provided with insulation properties.
The plasma chamber 29 can be moved by the XY stage 14 together with
the substrate holder. The light 8 emitted from the plasma 30 and
used for exciting the electrons in the insulator is transmitted
through the light transmission substance 27 just under the sample
26, and then the light 8 is reflected by the reflecting mirror 9
fixed to the chamber so as to be irradiated on the ion beam
irradiation area. The light 8 irradiated from many directions is
irradiated up to the conductive thin film 20 grounded by the
substrate holder, thereby grounding the charged particles. The
sample 26, just like in the above embodiments, is transformed into
a conductive material due to the irradiation of the light 8, so
that the charged ions in the irradiated ion beam 2 are not
accumulated in the insulator; rather, they are ejected up to the
grounded portion.
After this, the ion beam is scanned on the substrate, thereby
detecting the secondary particles ejected from the surface of the
substrate using the secondary particle detectors and observing the
scanning ion image. This ion image makes it possible to observe,
process, and analyze a desired area. The wavelength of the light 8
used here for exciting the electrons in the insulator can also
excite the sample 26 having insulation properties. Although the
plasma 30 used as an exciting light source is placed at the back
side of the sample 26 in FIG. 3, the plasma chamber 29 may be
placed on top of the sample 26, so that the light 8 emitted from
the plasma 30 and used for exciting the electrons in the object
insulator is irradiated on the surface of the sample 26, unless the
chamber 29, when placed there, affects the observation and
processing carried out using a charged beam. The substances that
transmit the above light 8 are MgF2, Life, etc.
<Fourth Embodiment>
The fourth embodiment of the present invention involves a method of
irradiating light for exciting the electrons in an object insulator
on defects of a phase shifting mask along the same axis as that of
the charged beam using a CARAT scope. Hereunder, the method in the
fourth embodiment will be described with reference to FIG. 4. In
FIG. 4, numeral 32 denotes a CARAT scope. Just like in the above
embodiments, an ion beam 2 is used for correcting defects. At
first, the position of the object defect 22 is detected using a
defect inspecting unit, and then, according to the coordinate data
which identifies the detected defect position, the possible
position of the defect 22 is moved to a location just under the
light axis of the ion beam 2. Then, the light 8 emitted from the
light source 7 and used for exciting the electrons in an object
insulator is irradiated on the sample. The light 8 is then
irradiated in the ion beam irradiation area along the same axis as
that of the ion beam 2 using the CARAT scope 32. The CARAT scope 32
is provided with a hole for passing the ion beam 2, so that the ion
beam 2 is irradiated on a given portion on the surface of the
sample through this hole.
The light 8 for exciting the electrons in the object insulator is
irradiated up to the conductive light-proof film 20 grounded by the
substrate holder, thereby grounding the charged particle in the
insulator. The insulator formed on the transparent substrate
provided with insulation properties, as in the above embodiments,
is transformed into a conductive material due to the irradiation of
the light 8, so that the charged particles of the ion beam 2 are
not accumulated in the insulator; rather, they are ejected up to
the grounded portion. After this, the ion beam 2 is scanned on the
sample, whereby the secondary particles ejected from the surface of
the substrate are detected by the secondary particle detectors and
the ion scanning image can be observed. The position of the defect
22 of the phase shifter is detected from this scanning ion image.
The ion beam 2 is irradiated only on this defect portion, thereby
removing or correcting the defect 22. In addition, if the
wavelength of the light 8 for exciting the electrons in the
insulator can excite the insulating transparent substrate 11 and
the substrate 11 is made of quartz, an ultraviolet light should
preferably be used at a wavelength of 150 nm or under.
<Fifth Embodiment>
The fifth embodiment of the present invention involves a method of
irradiating light for exciting the electrons in an object insulator
on defects of a phase shifting mask from many directions using
optical fibers. Hereunder, the method used in the fifth embodiment
will be described with reference to FIG. 5. In FIG. 5, numeral 33
denotes optical fibers. Just like in the above embodiments, an ion
beam 2 is used for correcting defects. At first, the position of
the object defect 22 is detected using a defect inspecting unit,
and then, according to the coordinate data of the detected defect
position, the possible position of the defect 22 is moved to a
location just under the light axis of the ion beam 2. Then, the
light 8 emitted from the light source 7 and used for exciting the
electrons in the object insulator is irradiated on the sample.
The light 8 emitted from the light source 7 and used for exciting
the electrons in the object insulator is then branched into optical
fibers 33, so that the light 8 is irradiated in the ion beam
irradiation area from many directions through those optical fibers.
The light 8 is irradiated up to the conductive light-proof film 20
grounded by the substrate holder, thereby grounding the charged
particles in the insulator. The insulator formed on the transparent
substrate provided with insulation properties, just like in the
above embodiments, is transformed into a conductive material due to
the irradiation of the light 8, so that the charged particles of
the ion beam 2 are not accumulated in the insulator; rather, they
are ejected up to the grounded portion. After this, the ion beam 2
is scanned on the sample, so that the secondary particles
discharged from the surface of the substrate are detected by the
secondary particle detectors and the ion scanning image can be
observed. The defect 22 of the phase shifter is detected from this
scanning ion image. The ion beam 2 is then irradiated only on this
defect portion, thereby removing or correcting the defect 22. In
addition, if the wavelength of the light 8 for exciting the
electrons in the insulator can excite the insulating transparent
substrate 11 and the substrate 11 is made of quartz, an ultraviolet
light should preferably be used at a wavelength of 150 nm or
under.
<Sixth Embodiment>
The sixth embodiment of the present is shown in FIG. 6. In this
embodiment, an ion beam is used as the charged beam described above
and a liquid crystal TAFT substrate is used as a sample with an
insulator formed thereon. In FIG. 6, numeral 34 denotes a probe, 35
denotes an insulator film, and 36 denotes a gate line. Reference
numerals 37 and 38 denote data lines, and 39 denotes a transparent
dot electrode. If a break failure 22 occurs in part of the data
line or gate line of the liquid crystal TAFT substrate used for a
projector, etc., whose size per one pixel is small, the TAFT
substrate causes a line defect. The ion beam 2 is used for
detecting the defect 22. At first, the position of the object
defect 22 is detected using a defect inspecting unit, and then,
according to the coordinate data which identifies the detected
defect position, the possible position of the defect 22 is moved to
a location just under the light axis of the ion beam 2. Then, the
light 8 emitted from the light source 7 and used for exciting the
electrons in the object insulator is irradiated in the ion beam
irradiation area.
Part of the light 8 emitted from the light source 7 and used for
exciting the electrons in the object insulator is reflected by the
reflecting mirror 9 attached to the probe 34, and then is
irradiated in the ion irradiation area from the direction in which
it is deflected by the reflection mirror 9. Grounding of the
insulator film transformed into a conductive material is carried
out by making the probe, which is grounded beforehand, come in
contact with the insulator film directly. The insulator film 35,
just like in the above embodiments, is transformed into a
conductive material due to the irradiation of the light 8, so that
the charged particles of the ion beam 2 are not accumulated in the
insulator film; rather, they are ejected up to the grounded
portion. After this, the ion beam 2 is scanned on the substrate,
thereby detecting the secondary particles ejected from the surface
of the substrate using the secondary particle detectors and
observing the scanning ion image.
The position of the defect 22 of the TAFT substrate is detected
from this scanning ion image, and an area where the ion beam 2 is
to be irradiated is set. The ion beam 2 is then irradiated only on
the defect portion, thereby removing or correcting the. defect. The
wavelength of the light 8 for exciting the electrons in the object
insulator must be a wavelength that can excite the transparent
substrate provided with insulation properties. Instead of the
reflecting mirror 9 mounted on the probe 34, however, the probe 34
itself may be provided with reflecting properties by using, for
example, aluminum as the material of the probe 34. If the subject
charged beam irradiating apparatus is provided with a nozzle, the
nozzle may be used to ground and reflect the charged particles in
the insulator instead of the probe.
<Seventh Embodiment>
The seventh embodiment of the present invention involves a method
of grounding a substrate provided with insulation properties, which
is transformed into a conductive material, as in the above
embodiments. Hereunder, the grounding method is realized with a
belt-like light for exciting the electrons in the insulator formed
on the object substrate, as will be described with reference to
FIG. 7(a) and FIG. 7(b). In FIG. 7(a), numeral 40 denotes a flat
cylindrical convex lens and 41 denotes a flat cylindrical concave
lens. When observing and processing a phase shifting mask at a
portion thereof which is close to the outside edge of the
substrate, the portion can be grounded by irradiating the light 8
up to the substrate holder, but it is difficult to ground isolated
patterns in the center portion of the phase shifting mask. The two
cylindrical lenses are used to solve such a problem.
At first, part of the light 8 enters the prism 25 and the rest of
the light 8 is directed to the reflecting mirror 9. The light 8
reflected by the reflecting mirror 9 is then irradiated in the
charged beam irradiation area. The light 8 which enters the prism
25 is deflected and its irradiation area is expanded in a single
axial direction by both flat convex cylindrical lens 40 and flat
concave cylindrical lens 41 (FIG. 7(b)) so as to effect grounding.
The belt-like light 8, whose irradiation area is expanded by these
two cylindrical lenses, is irradiated in the charged beam
irradiation area from a direction different from that of the light
coming from the reflecting mirror 9. Since the insulator formed on
the transparent substrate 11 provided with insulation properties is
transformed into a conductive material due to the irradiation of
the light 8, just like in the above embodiments, the charged
particles of the irradiated charged beam 2 are not accumulated in
the insulator; rather, they are ejected up to the grounded
portion.
After the particles are grounded as described above, the charged
beam 2 is irradiated for scanning the substrate and detecting the
secondary electrons or ions ejected therefrom using secondary
particle detectors, thereby observing and processing the surface of
the object substrate. In addition, the lenses 40 and 41 for
deflecting the light 8 should be drivingly structured as needed so
that a grounded conductive film can be selected. Although the
irradiation area is expanded only in the single axial direction in
this embodiment, the irradiation area may be expanded radially in
multi-axial directions.
<Eighth Embodiment>
The eighth embodiment of the present invention involves a method of
grounding a sample having insulation properties, whose surface
insulator is transformed into a conductive material, just like in
the above embodiments. Hereunder, the grounding method carried out
by scanning the light 8 for exciting the electrons in the object
insulator will be described with reference to FIG. 8. In FIG. 8,
numeral 42 denotes a rotary polygonal reflecting mirror. When
observing and processing the sample having insulation properties,
whose surface is covered by an insulator film, at a portion close
to the outside edge of the substrate, as in the seventh embodiment,
the portion can be grounded by irradiating the light 8 up to the
grounded substrate holder. However, it is difficult to ground the
center area covered by an insulator film. This polygonal reflecting
mirror 42 is thus used to solve this problem.
At first, part of the light 8 for exciting the electrons in the
object insulator is directed to the polygonal reflecting mirror 42
and the rest of the light 8 is directed to the reflecting mirror 9.
The light 8 reflected by the reflecting mirror 9 passes through the
light transmission substance 27, and then it is reflected again by
the reflecting mirror 9 and irradiated onto the charged beam
irradiation area. On the other hand, the light reflected by the
polygonal reflecting mirror 42 is irradiated onto the charged beam
irradiation area from a direction different from that of the light
reflected by the reflecting mirror 9. The polygonal reflecting
mirror 42, when rotated, allows the light 8 to scan an area ranged
from the charged beam irradiation area to a grounding area, thereby
ejecting charged particles therefrom.
Since the surface of the sample 26 having insulation properties is
transformed into a conductive material in response to irradiation
by the light 8. as in the above embodiments, the charged particles
of the irradiated charged beam 2 are not accumulated in the
insulator; rather, they are ejected up to the grounded portion due
to the scanning of the light from the polygonal reflecting mirror
42. After the charged particles are grounded in this way, the
focused charged beam 2 is scanned on the substrate, thereby
allowing the secondary electrons or ions ejected from the substrate
to be detected by the secondary particle detectors. It is thus
possible to observe or process and analyze the surface of the
substrate.
<Ninth Embodiment>
The ninth embodiment of the present invention involves a method of
irradiating light in the form of pulses for exciting the electrons
in the insulator described in the above embodiments. Hereunder, the
light pulse irradiating method will be described with reference to
FIGS. 9(a) and 9(b). In FIG. 9(b), numeral 43 denotes a light-proof
disc and 44 denotes a hole for passing the object light. The sample
to be observed and processed is not to be continuously altered nor
processed by the light 8 for exciting the electrons in the object
insulator. Especially when a gas is used together with the charged
beam, the gas may react with the light 8, thereby accelerating the
processing work. This is why the light 8 is irradiated in pulses in
this embodiment, thereby transforming the insulator into a
conductive material, as well as protecting the surface of the
substrate from damage as much as possible.
In order to irradiate the light 8 for exciting the electrons in the
object insulator in a pulse-like manner, the light-proof disc 43
provided with a light transmission hole 44 is rotated in the light
path between the light source 7 and the substrate. According to
this method, only when the light-passing hole 44 is aligned with
the light axis will the light 8 be irradiated; and, the light 8 is
blocked in other cases. And, the irradiation time is determined by
the size of the light transmission hole 44 provided for the
light-proof disc 43, so that the minimum necessary time for
transforming the insulator into a conductive material can be set.
The surface of the object substrate can thus be observed, and
processed/corrected as needed just like in the above embodiments.
In order to generate such light pulses, the light source also may
be controlled by a clock signal.
The method for irradiating the light 8 in a pulse-like manner can
also be applied to the first to eighth embodiments described above.
If the method is applied to any of those embodiments, it is
possible to reduce the influence of the irradiation of the light 8
on the detection of secondary electrons by shifting the timing for
irradiating the ion beam on a sample from the timing for
irradiating the pulsed light 8, thereby avoiding simultaneous
irradiation of both the ion beam and light 8.
The charged beam irradiating apparatus according to the above
embodiments may be a focused ion beam irradiating apparatus, a
scanning electron microscope, an Auger electron spectroscope, an
IMA (Ion Microprobe Analyzer), and an SIMS (Secondary Ion Mass
Spectrometry), for example.
* * * * *